The present invention relates to a loop transmission system having transmission stations connected by loop transmission lines and, more particularly, to a loop transmission system suitable for a digital integrated ring network in which data terminals and non-data terminals can coexist as data processors connected with the transmission stations.
Typical prior art technique for a digital integrated ring network, is described in papers such as C & C--NET LOOP 6830 Universal Link System: NEC Technical Report Vol. 36, No. 7/1983: Ito et al., pp. 32 to 38. In the transmission system disclosed in this report, the circuit exchange function is realized by a plurality of time sharing time slots. This requires a number of the aforementioned time slots, when a large volume of traffic such as digitized video data is to be processed as the transfer data, and the amount of network simultaneous storage is severely limited. For ring network topology, there exists a system employing a star network in which the respective relay lines are concentrated at one place, as is disclosed in "A Local Communications Network Based on Inter-connected Token-Access Rings: A Tutorial: IBM J. RES. DEVELOP Vol. 27, No. 5, 1983: C. Strole: pp. 481 to 496. However, this system aims at improving its reliability, and the circuit switching means called a "wiring concentrator" has a construction and operation designed only to bypass a a malfunctioning station but it does not improve the transmission performance of the system in the least.